Check the hose clips for tightness and inspect the trunking for any cracks or splits and also every the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best exaggeration to locate a leak is to have the engine admin and warm and then vaporizer lighter gas /propane or brake cleaner concerning each joint in turn. If the engine rev s going on you ve found your leak.
Its afterward worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will every outcome in insufficient fuel innate delivered to the engine. Might furthermore be worth cleaning out the idle rapidity manage motor / valve as these acquire clogged up when carbon and some brake cleaner washed through helps free things off.
following I begin the car, the engine surges going on between 1200 and 2000 rpm incite and forth. I changed the IAC and the TPS as soon as no alter in symptoms. I have noticed that several Lexus SC's have this thesame issue. Prior to this I would have to adapt the idle quickness screw to lower the rpm and it would retain for a while. Now, the engine is every time surging to the point where I cannot steer it for warning of damage to the steer train. Any experienced solution?